Relativistic quantum field theory is the adequate theoretical framework
to formulate the commonly accepted theory of the fundamental interactions,
the Standard Model of the strong and the
electroweak interactions [1]}, [2]}, [3]}, [4]}.
The Standard Model summarizes our present knowledge of the basic
constituents of matter and their interactions.
It is a gauge invariant quantum field theory based on
the symmetry group \(SU(3)\times SU(2)\times U(1)\) ,
with the colour group \(SU(3)\)  for the strong interaction and
with \(SU(2)\times U(1)\)  for the electroweak interaction
spontaneously broken by the Higgs mechanism.
The renormalizability of this class of theories
allows us to make precise predictions for measurable quantities
also in higher orders of the perturbative expansion, in terms of a
few input parameters.
The higher-order terms
contain the self-coupling of the vector bosons as well as their
interactions with the Higgs field and the top quark,
even for processes at lower energies
involving only light fermions.
Assuming the validity of the Standard Model, the presence of the
top quark and the Higgs boson in the loop contributions to electroweak
observables allows us to obtain indirect
significant bounds on their masses from
precision measurements of these observables.
The only unknown quantity at present is the Higgs boson.
Its mass is getting more and more
constrained by a comparison of the
Standard Model predictions with the experimental data,
preparing the ground for a crucial test at the LHC.
